Steel alloy



Patented Feb. 13, 1934 UNITED STATES STEEL ALLOY George Charlton, Detroit, Mich, assignor to Wilcox-Rich Corporation, a corporation of Michigan No Drawing. Application May 27, 1929 Serial No. 366,533

1 Claim.

The principal object of my invention is to provide an alloy steel which will not form an objectionable scale when used in articles which are subjected to high temperatures in use.

Another object of my invention is to provide an alloy steel from which exhaust valve, ring inserts for valve seats, and the like, for internal combustion engines may be made, and which will resist the corroding and scale forming influences of the high temperatures and gases which are generated in internal combustion engines.

Another object of myinvention is to provide an alloy steel having the above properties, and which may be readily forged to form valves or the like, or any other type of forging, and which may be softened so that it may be easily ,ma-

. chined, and then re-hardened to provide the necessary wearing qualities.

I attain the above objects by adding the elements of zirconium and chromium to other elements commonly present in steel, and have found that the alloy of which the following analysis is typical, will produce the result desired:

Per cent Carbon l .48 Manganese .31 Silicon .50 Chromium 7.93 Zirconium 1. 14

Balance iron and it appears from experiment that it is the presence and retention of the zirconium and chromium elements in the final product which produce the desired resistance to the formation of scale, even at high temperatures.

The elements manganese, silicon, phosphorus and sulphur are present in amounts common to ordinary steels or alloy steels and their presence is not of suflicient quantity to affect the properties noted.

I have also found that as the zirconium content is increased in proportion to a given amount of chromium, the scale resisting qualities of the alloy is increased. This condition obtains until the chromium content amounts to about 10 or 14 per cent. When the chromium content is increased to between 10 and 20 per cent, the zirconium content may be decreased,- and the scale resisting quality of the alloy will be greater than when the zirconium content is greater in proportion to the chromium content, although in both cases a satisfactory alloy is obtained.

The following is the analysis range covered by the two series or types mentioned:

Carbon .25 to 1.50 per cent Manganese 1.50 per cent maximum Silicon .70 per cent approx. Phosphorus sulphur--. 035 per cent maximum Chromium 1.00 I to 20.00 per cent Zirconium 1. 00 to 6.00 per cent Balance iron v The following is a typical analysis of the series in which the proportion of the zirconium content 4.00 per cent Balance iron And the following is a typical analysis of that series in which the proportion of the chromium content and the zirconium content are respectively increased and decreased:

Carbon 1.25 per cent Manganese 80 per cent Silicon .80 per cent Phosphorus sulphur .035 per cent or less Chromium 20.00 per cent Zirconium 2. 00 per cent Balance iron It may be noted that the iron is always present in what may be termed a preponderant amount (exceeding 50%) and that any of the analyses set forth will produce a steel alloy from which valves or seats for internal combustion engines may be made by the usual forging processes, which will not scale objectionably when subjected to high temperatures in use. When it is desired to increase the hot strength of the article, from .5 to 5% of the elements of tungsten, molybdenum, vanadium or nickel may be added without affecting the desirable scale resisting quality produced by the zirconium and chromium. It is to be understood, however, that my invention comprises steel alloys having and retained in the final product the chromium and zirconium contents in amounts within the ranges described, which produce the desired quality of resistance to oxidation at high temperatures, and give hot strength.

What I claim is:

A steel alloy including about 20.00 per cent chromium, 2.00 per cent zirconium, 1.25 per cent carbon, .80 per cent manganese, .80 per cent silicon, a minimum amount of phosphorus or sulphur, and the balance iron.

' GEORGE CHARLTON. 

